1. Field of the Invention
The present invention relates to tennis rackets having intersecting strings combined with protrusions for enhancing the frictional grip between the racket and the ball for effecting greater directional ball control as well as extending the useful life of the racket strings.
2. Description of the Prior Art
Being able to accurately control the placing of the ball when hit by the racket as well as the ball spin with greater facility makes it easier for the average tennis player to execute certain type of shots effectively. When a player is able to control the placing of the ball as well as the spin of a tennis ball with greater precision, the player can improve certain types of shots including "drop shots", "slicing strokes", "top-spin" as well as "under spin" shots.
Tennis rackets have previously been designed with protrusions for affecting greater control of the spin of the ball upon impact with the racket strings to result in greater directional control. In addition, there have also been earlier attempts at reducing friction between the intersecting strings caused by the impact of the ball on the intersecting strings, such as, by reducing or preventing sliding of one string with respect to the transversely directed string at the string intersections.
Examples of prior art concerned with improving ball control including spinning as well as lengthening the life of the tennis racket strings include the following patents. U.S. Pat. No. 763,059 to J. E. Hyde et al. incorporates knots at intervals along lengths of individual strings as well as at the intersections of the strings, as illustrated in FIG. 5 U.S. Pat. No. 1,682,199 to R. H. Smilie interposes a double concave disc at the intersections of the racket strings for better absorption of the ball impact force as well as reducing sliding of the strings themselves. Smilie also uses rubber type wedge grooves in order to improve gripping of the ball. U.S. Pat. No. 1,531,778 to E. F. Gallaudet discloses twine which is wrapped over the intersections of the tennis racket strings in order to prolong the life of the strings as well as for greater ball gripping control. British patent No. 331,925 to F. W. Donisthorpe discloses using an adhesive at the intersections of the racket strings for preventing wear and tear of the strings at those locations. U.S. Pat. No. 4,095,790 to Swiecicki increases the friction grip of the racket strings on the tennis ball by including protuberances on the intersections of the strings. In addition, the following patents and article also pertain to the design of tennis racket strings: U.S. Pat. Nos. 3,926,431, 4,078,796 and 4,349,198; Sports Illustrated article, "A Weighty Matter of Spagletti and Tennis Balls" by J. D. Reed, Apr. 3, 1978.